Non-volatile memory, such as flash memory, has been widely used in storage devices, such as removable flash memory cards, USB flash drives, and solid-state drives (SSD). Data stored in the flash memory might not be able to persist for a long period of time, which is often referred as data retention problem. In addition, data stored in an NAND flash may suffer from disturbance effects, including erase disturb, program disturb, and read disturb. For example, reading data from a page in an NAND flash may disturb the data stored in neighboring pages within the same block. Thus there is a need for a storage device and associated control method to enhance the data reliability in the flash memory.